According to Stein, the Nets are worried about their ability to re-sign guard Shaun Livingston in free agency and want to shore up their backcourt:

The Nets, sources say, are already weighing their backcourt options because they’re concerned about losing Livingston to a richer offer than league rules will allow Brooklyn to make in free agency after Livingston exceeded all expectations last season playing on a minimum contract.

Thornton, who arrived in Brooklyn after a mid-season trade with Sacramento, has only one year left on his contract. Jack is under contract for more than $12 million total over the next two seasons.